PRESENCE 




OF 



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NEW YORK CITY. 


A Paper Read before the American Institute of Mining 

t 

Engineers, at the Harrisburg Meeting, October, 1882. 


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AUTHOR’S EDITION. 

1882 . 
















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[TRANSACTIONS OF THE AMERICAN INSTITUTE OF MINING ENGINEERS.] 

PRESENCE OE TELLURIUM IN COPPER. 

BY T. EGLESTON, PII.D., NEW YORK CITY. 

(Read at the Harrisburg Meeting, October, 1882.) 

Some months ago samples of black oxide of copper and of pig 
copper from Colorado were sent to me to examine for arsenic and 
antimony. I examined them both by the blow pipe, and in the wet 
way, but found none present. 

A quantity of this material was purchased by a large metallurgical 
works, but when they attempted to refine it they pronounced it to be 
full of arsenic and antimony, so much so, that their furnaces were, 
as they said, “ poisoned,” and rendered unfit for refining. I then 
re-examined the samples, and at the same time some of the material 
which had “ poisoned ” the furnaces, and found no traces of arsenic 
or antimony when the usual amounts for analysis were used, but on 
taking very large amounts I found traces merely, in some parts of 
the sample, but not in all. As it was a matter of interest to ascertain 
what the white substance that “ poisoned ” the furnace was, I sent to 
the works making the black copper, and obtained some of the matte 
from which the black copper was made; 1 took careful samples, both 
of it and the black copper and the refined copper. I then found 
the impurity to be tellurium, a substance not heretofore known as 
occurring in copper. I give below one analysis of the matte, two of 
the black, and one of the refined copper: 






Refined 


Matte. 

Black Copper. 

Copper. 

Copper, 

. 55.02 

97.120 

98.090 

99.705 

Gold, .... 

0.06 

— 

— 

— 

Silver, 

. 0.40 

0.132 

0.128 

0.135 

Lead,.... 

. 17.87 

0.777 

0.757 

none. 

Zinc and nickel, 

. 2.22 

0.070 

0.100 

0.024 

Iron, .... 

. 4.18 

0.130 

0.080 

0.031 

Sulphur, 

. 20.02 

0.236 

* 

trace. 

Tellurium, . 

. 0.12 

0.093 

0.097 

0.083 

Arsenic, f. 

* 

0.006 

* 

0.091 

Slag, etc., . 


1.270 

0.192 



99.89 

99.834 

99.444 

100.069 

* dSTo traces were found with the blow pipe. 




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PRESENCE OF TELLURIUM IN COPPER. 


The mattes and the black copper are results of the treatment of 
copper ores with the tellurium ores of Colorado. In the laboratory 
no traces of white fumes were shown on charcoal, but when the 
metal in the furnace was subjected to the process of “ dry- roasting,” 
as was unintentionally done, very dense white fumes were given off. 
When refined and cast into cake, it had the ordinary appearance of 
cake copper. It was then reheated for rolling in the ordinary way, 
showing no signs of'impurity. At the first pass in the rolls, very 
fine cracks showed themselves, which opened in succeeding passes. 
At a thickness of about 0.03 meter the cracks on either side nearly 
penetrated the cake, and at about 0.008 meter it began to fall to 
pieces. It was heated and rolled at different temperatures, but 
always with the same result. 

When cold the metal is tough and malleable. Although the 
cakes in the moulds showed no coating, when they were heated 
repeatedly and allowed to cool in the air they became covered with 
a white powder, which proved to be the oxide of tellurium. The 
copper, as it comes from the cake moulds, has every appearance of 
being good copper. 

This is the first time, so far as I know, that the presence of tel¬ 
lurium has been detected in commercial copper. But very little of 
it is removed in the treatment, as the four analyses show. 

It is surprising how very small a quantity renders the copper 
red short, and consequently worthless for rolling. 







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